Ribot
From Sonic Retro
The Ribot (referred as as Keroppo in the Japanese Manual) is a robotnik frog enemy found in Launch Base Zone. This stationary badnik has three ways of attacking: swinging a metallic ball through the air in circles, punching the ground with a pair of weights or sweeping the ground with a weight on each hand. Avoid the weights, and destroy them with a spin or jump. "Kero-kero" is Japanese for the onomatopoeia "ribbit".